CERN: updates tagged "LHC"http://home.web.cern.ch/about/updates/LHC
enAn international blog series from ATLAShttp://home.web.cern.ch/about/updates/2015/07/international-blog-series-atlas
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<iframe allowfullscreen="" frameborder="0" height="450" src="//cds.cern.ch/video/ATLAS-MOVIE-2015-005-001?showTitle=true" width="100%"></iframe><p><figcaption>(Video: ATLAS/CERN)</figcaption></p>
<p>More than 3000 scientists from all over the world, including about 1000 graduate students, collaborate on the <a href="/about/experiments/atlas">ATLAS experiment</a> – an all-purpose detector on the <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC). The detector, which first started taking data in 2008, is investigating a wide range of physics, from the search for the <a href="/topics/higgs-boson">Higgs boson</a> to <a href="/about/physics/extra-dimensions-gravitons-and-tiny-black-holes">extra dimensions</a> and particles that could make up <a href="/about/physics/dark-matter">dark matter</a>.</p>
<p>The detector is currently taking data from collisions in the LHC at <a href="/about/updates/2015/05/first-images-collisions-13-tev">13 teraelectronvolts</a> (TeV). In the video above you can see how members of the collaboration fared on 3 June 2015, when beams collided at this new energy in the LHC for the first time.</p>
<p>The new blog series "From ATLAS around the World," showcases the diversity of people, jobs and research topics it takes to keep the ATLAS experiment up and running. Contributors come from as far afield as Turkey, Japan, Hong Kong, Australia, South Africa.</p>
<p>Ever wondered how many Turkish physicists it takes to blog from the Bosphorous? What it's like to be a physicist down under? Or even where you can meet a giraffe at a physics workshop?</p>
<p>Check out <a href="http://atlas.ch/blog/?cat=68"><em>From ATLAS around the World</em></a></p>
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Mon, 20 Jul 2015 12:46:05 +0000Cian O'Luanaigh59305 at http://home.web.cern.chDiscovery of a new class of particles at the LHChttp://home.web.cern.ch/about/updates/2015/07/discovery-new-class-particles-lhc
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<img typeof="foaf:Image" src="http://home.web.cern.ch/sites/home.web.cern.ch/files/styles/medium/public/image/update-for_the_public/2015/07/pentaquarks.jpg?itok=0UkCZVDs" width="800" height="318" alt="" /> </div>
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<p>Possible layout of the quarks in a pentaquark particle. The five quarks might be tightly bound (left). They might also be assembled into a meson (one quark and one antiquark) and a baryon (three quarks), weakly bound together (Image: Daniel Dominguez)</p>
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<p>The <a href="http://home.web.cern.ch/about/experiments/lhcb">LHCb</a> experiment at CERN’s <a href="http://home.web.cern.ch/topics/large-hadron-collider">Large Hadron Collider</a> has reported the discovery of a class of particles known as pentaquarks. The collaboration has submitted today <a href="http://arxiv.org/abs/1507.03414">a paper reporting these findings</a> to the journal Physical Review Letters.</p>
<p>“The pentaquark is not just any new particle,” said LHCb spokesperson Guy Wilkinson. “It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over 50 years of experimental searches. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we’re all made, is constituted.”</p>
<p>Our understanding of the structure of matter was revolutionized in 1964 when American physicist Murray Gell-Mann proposed that a category of particles known as baryons, which includes protons and neutrons, are comprised of three fractionally charged objects called quarks, and that another category, mesons, are formed of quark-antiquark pairs. Antiquarks are quarks of <a href="http://home.web.cern.ch/topics/antimatter">antimatter</a>. Gell-Mann was awarded the Nobel Prize in physics for this work in 1969. This quark model also allows the existence of other quark composite states, such as pentaquarks composed of four quarks and an antiquark.</p>
<p>Earlier experiments that have searched for pentaquarks have proved inconclusive. Where the LHCb experiment differs is that it has been able to look for pentaquarks from many perspectives, with all pointing to the same conclusion. It’s as if the previous searches were looking for silhouettes in the dark, whereas LHCb conducted the search with the lights on, and from all angles. The next step in the analysis will be to study how the quarks are bound together within the pentaquarks.</p>
<p>Read the <a href="http://press.web.cern.ch/press-releases/2015/07/cerns-lhcb-experiment-reports-observation-exotic-pentaquark-particles">full Press Release</a>.</p>
<p>Read the <a href="http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#Penta">LHCb article.</a></p>
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Tue, 14 Jul 2015 07:20:12 +0000Corinne Pralavorio59185 at http://home.web.cern.chChasing clouds in the LHChttp://home.web.cern.ch/about/updates/2015/06/chasing-clouds-lhc
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<a href="/authors/corinne-pralavorio" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Corinne Pralavorio</a></p>
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<img typeof="foaf:Image" src="http://home.web.cern.ch/sites/home.web.cern.ch/files/styles/medium/public/image/update-for_the_public/2015/06/simulation-electron-flux.png?itok=effEdRaj" width="800" height="378" alt="" /> </div>
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<p>Simulation of the electron flux produced when the beam passes through the vacuum chamber. The lines show the electron flux, the colours the density of electrons. The higher the density, the brighter the colours. </p>
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<p>It’s time for a big summer clean in the <a href="http://home.web.cern.ch/topics/large-hadron-collider">Large Hadron Collider</a> (LHC), but you won't see operators armed with feather dusters sprucing up the 27-km machine. The pipes in which the beams circulate are already ultra-clean and <a href="http://home.web.cern.ch/about/engineering/vacuum-empty-interplanetary-space">ultra-high vacuum</a>: the pressure in the beam pipes is just 10<sup>-10</sup> or even 10<sup>-11</sup> millibars – similar to on the Moon.</p>
<p>However, despite the ultra-high vacuum, residual gas molecules remain trapped on the surface of the walls of the beam pipes, which also contain electrons. When the beams circulate, these electrons are emitted from the walls and accelerated by the beam’s electrical field. The accelerated electrons then hit the walls with enough energy to release the trapped molecules, thereby compromising the vacuum. At the same time, they set off an avalanche of even more electrons, forming electron clouds that can be dense enough to destabilise the beam. The electron-cloud phenomenon is amplified the higher the number of proton bunches in the beam and the more closely spaced they are.</p>
<p>The operators therefore need to dissipate the electron clouds before the LHC can run with more proton bunches. To do that, they've developed a beam scrubbing technique that involves circulating enough protons to release as many trapped gas molecules as possible from the metal and to reduce the rate of production of electrons on the walls of the pipe.</p>
<p>The operators will thus circulate intense beams (containing many bunches) but at low energies in order to improve the beam pipe surface. After a few days, the LHC will be ready to be ramped up to higher-intensity beams for physics and to restart with 50-nanosecond bunch-spacing. The number of bunches will be gradually increased to 1000 bunches per beam. Another scrubbing run will be performed in the summer to prepare the LHC for <a href="http://home.web.cern.ch/about/updates/2015/06/lhc-experiments-back-business-record-energy">operation with more bunches</a> spaced even more closely together later in the year.</p>
<p> </p>
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Thu, 25 Jun 2015 08:35:06 +0000Corinne Pralavorio58346 at http://home.web.cern.chLHC physicists preserve Native American voiceshttp://home.web.cern.ch/about/updates/2015/06/lhc-physicists-preserve-native-american-voices
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<a href="/authors/sarah-charley" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Sarah Charley</a></p>
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<p><em>This article is a stub. Read the <a href="http://www.symmetrymagazine.org/article/june-2015/lhc-physicists-preserve-native-american-voices">full article</a> over at </em>symmetry<em> magazine.</em></p>
<hr /><p>Berkeley physicist Carl Haber listened in astonishment as the first notes of the 1950s hit “Goodnight Irene” played through his computer.</p>
<p>“It was one of those moments you remember your whole life,” Haber says.</p>
<p>The song came from an old record, but no needle traced its grooves. Haber wasn’t listening to the record; he was listening to an image of the record, which then-postdoc Vitaliy Fadeyev had produced by scanning it with a high-powered microscope. A set of mathematical algorithms then interpreted the trenches embossed on the record’s surface and translated them into sounds.</p>
<p>Haber and Fadeyev were neither preservationists nor audio experts. Rather, they were, and still are, both particle physicists working on the <a href="/about/experiments/atlas">ATLAS</a> experiment, a cathedral-sized particle detector located on CERN’s <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC). Haber is at Lawrence Berkeley National Laboratory and Fadeyev is now at the University of California, Santa Cruz. They specialize in designing the delicate silicon detectors that record the charge, trajectory and momentum of particles produced immediately after the high-energy proton collisions.</p>
<p>In order to pick out particles like the <a href="/topics/higgs-boson">Higgs boson</a> from the cacophony of noise created during the high-energy collisions, the LHC detectors must be extremely precise—so precise that the inner detectors can distinguish between two particles separated by the width of a human hair.</p>
<p><figure class="breakout-left"><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/frances_densmore_recording_mountain_chief-s.jpg" /><figcaption>Ethnographer Frances Densmore with Blackfoot chief, Mountain Chief, during a 1916 phonograph recording session for the Bureau of American Ethnology. (Image: Wikimedia Commons)</figcaption></figure></p>
<p>To make these detectors, physicists use optical imaging to determine the shapes of the components. Then they apply mathematical algorithms to analyze the components’ dimensions and specialized machinery to piece them together with the precision of a few micrometers.</p>
<p>“It is a very powerful technique,” Haber says, “and I was very interested in what other applications it could have.”</p>
<p>Haber got his answer in the early 2000s on one of his many trips between Berkeley, where they were assembling the ATLAS detectors, and Silicon Valley, where he was purchasing detector materials and fabricating detector components.</p>
<p>“I was driving and my brain was swirling with all these thoughts of imaging, analyzing and processing,” Haber says. “I was thinking about its applications, when I heard an interview on the radio with Mickey Hart.”</p>
<p>Mickey Hart, the legendary drummer from the Grateful Dead, is an ethnographer and a huge proponent of preserving the heritage of music. During this radio interview, Hart explained that there are thousands of old recordings cataloging the music, language and culture of at-risk indigenous communities. But these recordings, Hart explained, are stored on archaic, sometimes warped or broken material.</p>
<p>“And I thought,” Haber says, “if you could take a recording and turn it into a picture, then you could extract the information by using these mathematical approaches we were applying to our physics research.”</p>
<p><strong>Read the rest of this article:</strong> "<a href="http://www.symmetrymagazine.org/article/june-2015/lhc-physicists-preserve-native-american-voices">LHC physicists preserve Native American voices</a>" – <em>symmetry</em> magazine</p>
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Fri, 12 Jun 2015 12:57:52 +0000Cian O'Luanaigh57735 at http://home.web.cern.chLHC experiments back in business at record energyhttp://home.web.cern.ch/about/updates/2015/06/lhc-experiments-back-business-record-energy
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<img typeof="foaf:Image" src="http://home.web.cern.ch/sites/home.web.cern.ch/files/styles/medium/public/image/update-for_the_public/2015/06/ccc_celebrates.jpg?itok=ifzdCZL7" width="800" height="534" alt="" /> </div>
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<p>In the CERN Control Centre, the LHC operations team as well as members of CERN management applaud the announcement of stable beams this morning at 10.40am (Image: Maximilien Brice/CERN) <a href="https://cds.cern.ch/record/2020852">more images</a></p>
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<p>The<a href="/topics/large-hadron-collider"> Large Hadron Collider</a> (LHC) started delivering physics data today for the first time in 27 months. After an almost two year shutdown and several months re-commissioning, the LHC is now providing collisions to all of its experiments at the unprecedented energy of 13 TeV, almost double the collision energy of its first run. This marks the start of season 2 at the LHC, opening the way to new discoveries. The LHC will now run round the clock for the next three years.</p>
<p>“With the LHC back in the collision-production mode, we celebrate the end of two months of beam commissioning,” said CERN Director of Accelerators and Technology Frédérick Bordry. “It is a great accomplishment and a rewarding moment for all of the teams involved in the work performed during the long shutdown of the LHC, in the powering tests and in the beam commissioning process. All these people have dedicated so much of their time to making this happen.”</p>
<p>Today at 10.40am, the LHC operators declared “stable beams”, the signal for the LHC experiments that they can start taking data. Beams are made of “trains” of proton bunches moving at almost the speed of light around the 27 kilometre ring of the LHC. These so-called bunch trains circulate in opposite directions, guided by powerful superconducting magnets. Today the LHC was filled with 6 bunches each containing around 100 billion protons. This rate will be progressively increased as the run goes on to 2808 bunches per beam, allowing the LHC to produce up to 1 billion collisions per second.</p>
<p>For more information see the <a href="http://run2-13tev.web.cern.ch/">live blog that covered events as they unfolded</a>.</p>
<p>See a <a href="http://cds.cern.ch/record/2020852?ln=en">gallery of images</a> from the day.</p>
<p><em>Added 5 June: </em></p>
<p><a href="https://cds.cern.ch/record/2022211">Watch a recording of the webcast from the day</a></p>
<p><a href="http://cds.cern.ch/record/2022239">Webcast: Q &amp; A session</a></p>
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Wed, 03 Jun 2015 10:29:46 +0000Cian O'Luanaigh57373 at http://home.web.cern.chLive blog: LHC experiments to start taking data at 13 TeVhttp://home.web.cern.ch/about/updates/2015/06/live-blog-lhc-experiments-start-taking-data-13-tev
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<p>Today's the day! The <a href="http://home.web.cern.ch/topics/large-hadron-collider">Large Hadron Collider</a> (LHC) is set to start delivering physics data to its experiments for the first time in 27 months.</p>
<p>After nearly two years of maintenance and repair, as well as several months of re-commissioning, the experiments at the world's largest particle accelerator are now ready to take data at the unprecedented energy of 13 teraelectronvolts (TeV) – almost double the collision energy of the LHC's first, three-year run. Data taking will mark the start of season 2 at the LHC, opening the way to new frontiers in physics.</p>
<p>For all the day's action, follow our Live Blog "<a href="http://run2-13tev.web.cern.ch/">LHC Season 2: New frontiers in physics</a>" where we'll be posting all the latest from the CERN Control Centre.</p>
<p>Or see a <a href="http://cds.cern.ch/record/2020852?ln=en">gallery of images</a> from the day.</p>
<p><em>Added 5 June: </em></p>
<p><a href="https://cds.cern.ch/record/2022211">Watch a recording of the webcast from the day</a></p>
<p><a href="http://cds.cern.ch/record/2022239">Webcast: Q &amp; A session</a></p>
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Wed, 03 Jun 2015 05:05:32 +0000Cian O'Luanaigh57365 at http://home.web.cern.chLHC Season 2: First physics at 13 TeV to start tomorrowhttp://home.web.cern.ch/about/updates/2015/06/lhc-season-2-first-physics-13-tev-start-tomorrow
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<p>In the early morning of Wednesday 3 June, the <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC) at CERN is set to start delivering physics data to its experiments for the first time in 27 months.</p>
<p>After nearly two years of maintenance and repair, as well as several months of re-commissioning, the experiments at the world's largest particle accelerator are now ready to take data at the unprecedented energy of 13 teraelectronvolts (TeV) – almost double the collision energy of the LHC's first, three-year run. Data taking will mark the start of season 2 at the LHC, opening the way to new frontiers in physics.</p>
<p>For all the day's action, follow our Live Blog "<a href="http://run2-13tev.web.cern.ch/">LHC Season 2: New frontiers in physics</a>" where we'll be posting all the latest from the CERN Control Centre, starting at 7am CEST.</p>
<p>The blog will guide you through key moments in the day, from injecting the counter-rotating beams of protons into the LHC and ramping their energy to 6.5 TeV each, to eventual particle collisions and the start of data taking at 13 TeV. A live webcast will also be available through the live blog.</p>
<p>For more about the big questions that the LHC experiments are tackling, check out “<a href="http://press.web.cern.ch/backgrounders/lhc-season-2-new-frontiers-physics">New frontiers in physics</a>” and <a href="/about/updates/2015/05/lhc-season-2-follow-people-frontiers-physics">follow the scientists at the forefront of particle physics</a>.</p>
<p>For more about the LHC and its second run, check out "<a href="http://press.web.cern.ch/backgrounders/lhc-season-2-facts-figures">LHC Season 2: Facts &amp; figures</a>" and "<a href="http://press.web.cern.ch/backgrounders/lhc-season-2-stronger-machine">LHC Season 2: A stronger machine</a>"</p>
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Tue, 02 Jun 2015 13:50:11 +0000Cian O'Luanaigh57327 at http://home.web.cern.chSmaller LHC collaborations to analyse collisions at 13 TeVhttp://home.web.cern.ch/about/updates/2015/06/smaller-lhc-collaborations-analyse-collisions-13-tev
<p class="field-byline-taxonomy">
<a href="/authors/cian-oluanaigh" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Cian O&#039;Luanaigh</a></p>
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<p>Some 100 metres underground, on the 27-kilometre ring of the <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC), sit four experiments the size of buildings. <a href="/about/experiments/atlas">ATLAS</a> and <a href="/about/experiments/cms">CMS</a> are general-purpose detectors designed to investigate a wide range of physics phenomena from <a href="/topics/higgs-boson">Higgs bosons</a> to dark matter; <a href="/about/experiments/alice">ALICE</a> specializes in studying <a href="/about/physics/heavy-ions-and-quark-gluon-plasma">quark-gluon plasma</a> – a state of matter thought to have existed moments after the <a href="/about/physics/early-universe">Big Bang</a> – and <a href="/about/experiments/lhcb">LHCb</a> is investigating the difference between matter and <a href="/topics/antimatter">antimatter</a> by analysing beauty quarks.</p>
<p>But these are not the only experiments at the world's most powerful particle accelerator. Three smaller experiments – TOTEM, LHCf and MoEDAL – will be among those searching for new physics when data taking begins, in early June, at the LHC's <a href="http://press.web.cern.ch/backgrounders/lhc-season-2-new-frontiers-physics">new energy frontier</a> of 13 teraelectronvolts (TeV).</p>
<p><figure class="cds-image breakout-left" id="CERN-EX-0906091-02"><a href="//cds.cern.ch/images/CERN-EX-0906091-02" title="View on CDS"><img alt="TOTEM,Roman Pot,Pot Romain" src="//cds.cern.ch/images/CERN-EX-0906091-02/file?size=medium" /></a><br /><figcaption>In the TOTEM experiment, detectors called '<a href="http://totem-experiment.web.cern.ch/totem-experiment/detectors/roman-pots/">Roman pots</a>' localise the trajectories of protons<span> (Image: Maximilien Brice/CERN)</span></figcaption></figure></p>
<p>The <a href="/about/experiments/totem">TOTEM</a> experiment takes precise measurements of protons as they emerge from collisions in the LHC at small angles to the beampipe. This region is known as the 'forward' direction. TOTEM detectors on both sides of the interaction point at CMS are spread across a total distance of almost half a kilometre. For the LHC's second run, the TOTEM and CMS collaborations plan to coordinate the use of their detectors to perform combined measurements with unprecedented accuracy.</p>
<p>"TOTEM will continue to give insights on the structure of the proton, as well as diffractive processes relevant in forward and cosmic-ray physics," says TOTEM spokesperson Simone Giani. "Combining TOTEM data with those of CMS will allow measurements of 'missing energy' with discovery potential in a phase space not accessible to former experiments."</p>
<p>The <a href="/about/experiments/lhcf">Large Hadron Collider forward</a> (LHCf) experiment measures neutral particles emitted at nearly zero degrees to the direction of the proton beam. Because these 'very forward' particles carry a large fraction of the collision energy, they are important for understanding the development of showers of particles produced in the atmosphere by high-energy <a href="/about/physics/cosmic-rays-particles-outer-space">cosmic rays</a>. To measure these particles, two detectors, Arm1 and Arm2, sit along the LHC beamline, at 140 metres either side of the ATLAS collision point.</p>
<p>"Since their birth around 2004 the LHCf detectors have been upgraded year after year, in such a way that their performance and radiation hardness have been greatly improved in view of the 13 TeV proton-proton run," says Lorenzo Bonechi, who leads a team for the LHCf collaboration in Florence, Italy. "The LHCf results at 7 TeV collisions are in good agreement with model predictions for forward photon and neutral pion productions but not for forward neutrons. The operation at 13 TeV collisions give us a great opportunity to confirm the results with collisions of about factor four higher energy in the laboratory frame and to test models more precisely than at 7 TeV."</p>
<p><a href="/about/experiments/moedal">MoEDAL</a>, the LHC's newest experiment, is designed to search for highly ionizing avatars of new physics such as magnetic monopoles. Its physics programme defines numerous scenarios that yield insights into such questions as: are there extra dimensions or new symmetries; does magnetic charge exist; and what is the nature of dark matter.</p>
<p>The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of over 200 square metres of nuclear track detectors – analysed offline by ultra-fast scanning microscopes – sensitive only to new physics. Second, with roughly one tonne of trapping detectors, it is able to capture particle messengers of physics beyond the <a href="/about/physics/standard-model">Standard Model</a> for further study. </p>
<p>"The MoEDAL experiment will begin to take data for the first time in June 2015," says MoEDAL spokesperson James Pinfold. "Any MoEDAL discovery would have a revolutionary impact comparable to that of the Higgs boson."</p>
<p>With data taking to start in early June, LHC experiments large and small are rearing to explore new frontiers in physics.</p>
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Mon, 01 Jun 2015 09:13:42 +0000Cian O'Luanaigh57292 at http://home.web.cern.chFirst images of collisions at 13 TeVhttp://home.web.cern.ch/about/updates/2015/05/first-images-collisions-13-tev
<p class="field-byline-taxonomy">
<a href="/authors/cian-oluanaigh" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Cian O&#039;Luanaigh</a></p>
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<img typeof="foaf:Image" src="http://home.web.cern.ch/sites/home.web.cern.ch/files/styles/medium/public/image/update-for_the_public/2015/05/screen_shot_2015-05-21_at_09.22.21.png?itok=2kAzn38K" width="800" height="594" alt="" /> </div>
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<p>Test collisions continue today at 13 TeV in the Large Hadron Collider (LHC) to prepare the detectors ALICE, ATLAS, CMS, LHCb, LHCf, MOEDAL and TOTEM for data-taking, planned for early June (Image: LHC page 1)</p>
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<p>Last night, <a href="/about/updates/2015/05/protons-set-collide-13-tev-prepare-physics">protons collided</a> in the <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC) at the record-breaking energy of 13 teraelectronvolts (TeV) for the first time. These test collisions were to set up systems that protect the machine and detectors from particles that stray from the edges of the beam.</p>
<p>A key part of the process was the set-up of the collimators. These devices which absorb stray particles were adjusted in colliding-beam conditions. This set-up will give the accelerator team the data they need to ensure that the LHC magnets and detectors are fully protected.</p>
<p>Today the tests continue. Colliding beams will stay in the LHC for several hours. The LHC Operations team will continue to monitor beam quality and optimisation of the set-up.</p>
<p>This is an important part of the process that will allow the experimental teams running the detectors <a href="/about/experiments/alice">ALICE</a>, <a href="/about/experiments/atlas">ATLAS</a>, <a href="/about/experiments/cms">CMS</a>, <a href="/about/experiments/lhcb">LHCb</a>, <a href="http://home.web.cern.ch/about/experiments/lhcf">LHCf</a>, <a href="http://home.web.cern.ch/about/experiments/moedal">MOEDAL</a> and <a href="http://home.web.cern.ch/about/experiments/totem">TOTEM</a> to switch on their experiments fully. Data taking and the start of the LHC's second run is planned for early June.</p>
<p><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/alice-2.png" /><figcaption>Protons collide at 13 TeV sending showers of particles through the ALICE detector (Image: ALICE)</figcaption></figure><br /><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/cms-collisions.jpg" /><figcaption>Protons collide at 13 TeV sending showers of particles through the CMS detector (Image: CMS)</figcaption></figure><br /><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/atlas.jpg" /><figcaption>Protons collide at 13 TeV sending showers of particles through the ATLAS detector (Image: ATLAS)</figcaption></figure><br /><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/lhcb_0.png" /><figcaption>Protons collide at 13 TeV sending showers of particles through the LHCb detector (Image: LHCb)</figcaption></figure><br /><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/katebrad/3trisb.png" /><figcaption>Protons collide at 13 TeV sending showers of particles through the TOTEM detector (Image: TOTEM)</figcaption></figure></p>
<p>Follow the experiments on Twitter for updates: <a href="https://twitter.com/ALICEexperiment">@ALICE Experiment</a>, <a href="https://twitter.com/ATLASexperiment">@ATLAS Experiment</a>, <a href="https://twitter.com/CMSexperiment">@CMS Experiment</a>, <a href="https://twitter.com/LHCbExperiment">@LHCb Experiment</a></p>
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Thu, 21 May 2015 08:13:22 +0000Cian O'Luanaigh56606 at http://home.web.cern.chProtons set to collide at 13 TeV to prepare for physicshttp://home.web.cern.ch/about/updates/2015/05/protons-set-collide-13-tev-prepare-physics
<p class="field-byline-taxonomy">
<a href="/authors/cian-oluanaigh" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">Cian O&#039;Luanaigh</a></p>
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<p>Over the next 24 hours, beams of protons should collide in the <a href="/topics/large-hadron-collider">Large Hadron Collider</a> (LHC) at the record-breaking energy of 13 teraelectronvolts (TeV) for the first time. This is one of the many steps required to prepare the machine before the LHC's second physics run can begin. The LHC Operations team plans to declare "stable beams" in the coming weeks – the signal for the LHC <a href="/about/experiments">experiments</a> to start taking physics data at this new energy frontier.</p>
<p>"We begin by bringing the beams into collision at 13 TeV, and adjusting their orbits to collide them head-on," says Ronaldus SuykerBuyk of the Operations team.</p>
<p>Last month <a href="/about/updates/2015/04/proton-beams-are-back-lhc">proton beams were back</a> in the accelerator for the first time after two years of intense maintenance and consolidation. The <a href="/about/updates/2015/04/first-successful-beam-record-energy-65-tev">first beam at the record energy of 6.5 TeV</a> circulated on 10 April, and the <a href="/about/updates/2015/05/low-energy-collisions-tune-lhc-experiments">first collisions</a> – at the lower beam energy of 450 gigaelectronvolts (GeV) <span style="line-height: 20.7999992370605px;">–</span> followed.</p>
<p>The team has already checked and fine-tuned all the beam instruments, magnets and collimators along the 27-kilometre accelerator for collisions at 900 GeV. But when beam energy increases to 6.5 TeV, the beam parameters and orbits change significantly as compared to 450 GeV. In addition, the beams are focused down to a much smaller spot size within the experiments and as a consequence the location of collisions changes.</p>
<p>"When we start to bring the beams into collision at a new energy, they often miss each other," says Jorg Wenninger of the LHC Operations team. "The beams are tiny – only about 20 microns in diameter at 6.5 TeV; more than 10 times smaller than at 450 GeV. So we have to scan around – adjusting the orbit of each beam until collision rates provided by the experiments tell us that they are colliding properly."</p>
<p>The design of the LHC allows more than 2800 bunches of protons to circulate in each beam at a time. But the LHC Operations team will start collision tests with just one or two bunches per beam at the nominal intensity of 10<sup>11</sup> particles per bunch to ensure that all is running smoothly.</p>
<p><figure><img alt="" src="/sites/home.web.cern.ch/files/image/inline-images/coluanai/13tev-operations-team_0.jpg" /><figcaption>A member of the LHC Operations team monitors beam quality in the Large Hadron Collider (LHC) from a computer array in the CERN Control Centre (Image: Maximilien Brice/CERN)</figcaption></figure></p>
<p>Once they have found the points at which the beams interact optimally to give the most physics data, collimators have to be positioned accurately around the beam orbits to intercept particles that stray from the beam before they can hit magnets or detectors. "When the positioning of all collimators has been validated the LHC will switch over to production mode," says Wenninger, "and become a 'collision factory', delivering data to experiments." At this point, the experiments will switch on fully, and <a href="http://press.web.cern.ch/backgrounders/lhc-season-2-new-frontiers-physics">LHC Run 2</a> will begin.</p>
<p>In the meantime, the large LHC experiments <a href="/about/experiments/alice">ALICE</a>, <a href="/about/experiments/atlas" style="line-height: 20.7999992370605px;">ATLAS</a><span style="line-height: 20.7999992370605px;">,</span> <a href="/about/experiments/cms" style="line-height: 20.7999992370605px;">CMS</a><span style="line-height: 20.7999992370605px;"> </span>and <a href="/about/experiments/lhcb" style="line-height: 20.7999992370605px;">LHCb</a><span style="line-height: 20.7999992370605px;"> </span>will use the test data to check specific parts of their detectors for the upcoming physics run.</p>
<p>"The collisions at 13 TeV will allow us to further test all improvements that have been made to the trigger and reconstruction systems, and check the synchronisation of all the components of our detector," says CMS spokesperson Tiziano Camporesi. </p>
<p>“These data are precious to complete the fine tuning of the preparation for the run,” says ALICE spokesperson Paolo Giubellino. “ALICE has installed new detectors during the shutdown, and has significantly upgraded the trigger and readout. The validation of the new hardware will greatly benefit from the first data.”</p>
<p>"Although these collisions are not used for physics studies, they are useful for refining the synchronization of the readout time of different parts of the calorimeters and muon detectors," says LHCb spokesperson Guy Wilkinson.</p>
<p>"These 13 TeV data allow us to work on further improving the ATLAS detector readiness, following the recent 900 GeV collisions," says ATLAS spokesperson Dave Charlton. "The higher energies mean that we expect more active and energetic events, which will let us probe more deeply into the detector, for example."</p>
<p>Declaring "stable beams" will be only the beginning for the LHC Operations team. "We’re still working on the injection chain to the LHC, and finalising the collimators," says Wenninger. “And the machine evolves around you. There are little changes over the months. There’s the alignment of the machine, which moves a little with the slow-changing geology of the area. So we keep adjusting every day."</p>
<p>This week's collisions at 13 TeV are to check that CERN's flagship – the LHC – is sea-worthy. But we haven't yet begun the voyage to new frontiers.</p>
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Wed, 20 May 2015 15:30:02 +0000Cian O'Luanaigh56583 at http://home.web.cern.ch